I forgot to update you guys after I went to the dealership. They told me that "bi-stable" relay was stuck open causing the radio and SOS not to function. When they had the car hooked up to the computer, they were able to force the relay shut, but could not guarantee that it would never happen again. After that the radio worked fine and no SOS light was flashing for a couple weeks.
Well, it happened again when my battery went dead (a different issue all together). From what they said, this relay is soldered to the fuse box (not sure why anyone would think soldering a relay to the fuse box is a good idea) which means they want to replace the entire thing.
I have no plans to pay the dealership $800+ to replace the fuse box for some silly relay. I plan to remove the fuse box this weekend and see if I can't isolate the relay that is stuck open. I'm hoping that I can replace it myself (I'm more than confident in my soldering abilities to do this, depending on how tight the board is). Otherwise I suppose I will need a replacement fuse box.
Anyone fix this problem for good w/o replacing the fuse box?